#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=1e5;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}

bool check(LL x,LL a,LL b,LL c){
    if(a<=x){
        LL cnt=x-a;
        if(c<cnt) return false;
        else{
            c-=cnt;
        }
    }
    else{
        a-=x;
    }
    if(b+c>=x) return true;
    else return false;
}
int main(void)
{
  ///cin.tie(0);std::ios::sync_with_stdio(false);
  LL a,b,c;
  a=read();b=read();c=read();
  ///cout<<(a+b+c)/2*2<<"\n";
 /// return 0;
  LL l=0;LL r=1e18;
  while(l<r){
    LL mid=(l+r+1)>>1;
    if(check(mid,a,b,c)) l=mid;
    else r=mid-1;
  }
  cout<<l*2<<"\n";
return 0;
}
